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What to look for when buying a Car Diagnosis Machine : Part 1


If you are into serious car repair and maintenance; whether a garage, independent freelancing mechanic or just a motor vehicle enthusiast, then a diagnosis machine is a must have. The modern car is fitted with a ton of control modules and sensors some of which you never get to know till they fail. Without a good comprehensive diagnosis machine, it will be like shooting in the dark with the hope that your second guessing will land you to that failed component; a risky and expensive affair this will be. Our part one of “what to look for when buying a diagnosis machine” will be to dwell on what an ideal machine should have.

A genuine comprehensive diagnosis machine is not cheap, i repeat not cheap. If you spot a diagnosis machine that claims to cover all makes and models and carries all diagnostic protocols but is retailing at 30,000 kshs or thereof know this is a funny pick-up line that you are meant to laugh at. So what should a good comprehensive machine have:


A good comprehensive machine should support all car manufacturer protocols: J1850 VPW, ISO 9141-2/KWP2000, J1850 PWM, CAN, etc . Different car makers use different protocols so if a certain protocol is not supported by a diagnosis machine, then boom!!!! your machine will fall short of being comprehensive to handle cars on such protocols

A good diagnosis machine should handle all available control modules in a car. Today’s cars have a collection of control modules. These control modules operate everything from the power-train, braking, steering and suspension system to climate control, lighting, entertainment, communications and navigation. The technology is mostly incomprehensible to the average motorist, yet it provides all kinds of functions and capabilities that were not even on the radar a decade ago: things like Bluetooth connectivity, hands-free communication and email, automatic emergency braking, blind spot detection, adaptive cruise control, stability control, electronic steering and even key-less smart fobs that allow the vehicle to sense your approach, automatically unlock the doors for you and wake up the on-board electronics so you can be on your way.


Some of these modules include:

- ABS/traction control/stability control module

- Airbag (SRS) module

-Alarm module (or chime module) for anti-theft system

- Cruise control module

- Electronic steering module

- Fuel pump control module

-Injector driver module (such as FSD/PMD modules on GM diesel engines)

- Instrument cluster control module (which may be part of the cluster itself or a separate black box)

- Keyless entry module

- Lighting module

- Remote start/immobilizer module

- Suspension control module

- Transfer case module (4WD)

- Wiper motor control module

-Vehicle communication module (such as GM OnStar module)

- Plus all kinds of “mini” modules for power windows, power seats, heated/cooled seats, power sliding doors, door locks, sunroofs, air flow control doors inside the Heating Ventilation Air Conditioning (HVAC) system, and so on.


This highly sophisticated and complicated technology is wonderful as long as it is working. But when something goes amiss such as a module failure, communications bus failure or sensor fault, it can cause all kinds of problems sometimes in seemingly unrelated systems. The failure of a steering angle sensor may affect not only the electronic steering but also the stability control system since both need to know the position and turn rate of the steering wheel.

Diagnostics has become a major challenge for today’s technicians, and is totally beyond the abilities of most “local mechanics”. The reason why is that it takes sophisticated diagnostic equipment, the know-how to use that equipment and lots of experience to correctly diagnose many module-related faults. Many modules are replaced unnecessarily because the real problem was misdiagnosed (things like bad grounds, loose or corroded wiring connections or low voltage).

A good diagnosis Machine goes beyond reading the codes and erasing, it should offer you a possible online connections through wi-fi to a “database of reference”, to enable you find similar issues that other technicians have encountered and be able to resolve fully. An inexpensive scan tool that can read OBD powertrain codes (“P” codes) and CAN communication faults (“U” codes) usually cannot access body codes (“B” codes) and other subsystem codes (though a few can read ABS and air bag codes). What is usually required is a professional level scan tool (which is expensive but is supposed to cover a broad range of makes and models).

We will continue to expound on features of comprehensive vehicle diagnosis . : -

We sell Authentic Autel and Launch Diagnostic Machines: Call us on 0722 73 73 73

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